Magnesium base alloys



Patented May 23, 1933 UNITED STATES PATENT err-ice JOHN A. GANN AND FREDL. BEYNOLIOS, OF IIDLAND, IICEIGAH, ABBIGNOBB TO m DOW CHE'IICALCOHPANY, OF IIDLAN D, IICHIGAN, A CORPORATION OF IICHIGAN? IAGNESIUIBABE ALLOYS No Drawing.

The present invention relates to improved light-weight alloys in whichmagnesium is the predominating constituent. One object of our inventionis to produce magnesium base alloys having the characteristic lowspecific gravity approaching that of ma nesium that at the same timepossess a com ination of useful properties among which may be citedtoughness, malleabilit-y, and tensile strength, so as to-make thesealloys valuable for use in themechanical arts where lightness andstrength are essential. Other objects and advantages will appear as thedescri 'tion proceeds.

e binary alloys of magnesium and cadmium, wherein magnesium is presentin excess of 80 per cent, are known and some of their properties havebeen investigated. In-

. sofar as we are aware, however, no one has produced or investigatedthe ternary alloys containing over 80 per cent of magnesium which may bemade by adding relatively small amounts of zinc to the aforesaid binarymagnesium-cadmium alloys. We have discovered that by adding varyingamounts of i zinc to the above mentioned binary alloys,

useful alloys may be obtained that exhibit a combination of valuableproperties not possessed by either of the parent binary alloys, i. e.magnesium-cadmium or magnesium-zinc.

Accordingly, the alloys which are the subject of our invention containthe metals magnes'1um,cadm1um and zinc, wherein the magnesium content isin excess of 80 per cent and cadmium and 'zinc are present each in'amounts of over 0.5 per cent and the quantity of cadmium and zinctogether is less than 40 20 per cent of the total.

Examples of our improved ternary alloys are given in the table showingtheir properties measured on extruded samples of thealloys,.together'with the properties of the parent binary alloys ofcadmium and magnesi-.

Application filed February 15, 1982. Serial No. 888,105,

um, and of zinc and magnesium for comparison.

The data of the table indicates that the a tensile strength yield point.(defined as the load in lbs/sq. in. at which the stress-strain curvedeviates 0.1 per cent elongation from the modulus line), elongation andtoughness are improved by adding zinc ,to the t0 binar ma esium-cadmiumalloys without sacri eing ardness a preciably.

The ,malleability of t ese allo s is superior to the parent binaralloys. or exam lo,

the binary alloys 0 ma nesium containing 75 from 2 to 6 per cent 0cadmium may be forged, but in so doing slight cracking develops, escially at the outermost edges,

when they or ngs are made either by reesing between me or by hammeringan em- I- ploying the most suitable working temperatures. This crackihenomenon is exhibited also in the case 0 t e binary magnesium: zincalloys containing from 3 to 4'pe'r'cent of zinc, but in greater d ree onbeing 8} forged by pressing between ice, and it is,

vmoreover, practically impossible to produce a useful forging of suchalloys by hammering, since almost complete shattering occurs underhammer blows. On the other hand,-

by employing our new ternary alloys containin both cadmium and zinc, forexample, w ere the zinc content is from 1 to 4 per cent and that ofcadmium about 6 per cent and the balance magnesium forgings can be madereadily without cracking.

The hereindescribed magnesium base allo s may be cast, extruded,orwrought or otherwise shaped 0 methods commonly used for such alloys,but the proportions of cadmium and zinc are to be governed by theparticular application or shaping procedure preferred in a given case.For example, alloys coming within the scope of this invention, which areparticularly adaptable to hammer forging, may have a zinc contentpreferably of from 0.5 to 2 per cent and cadmium from 1 to 10 per cent.If the slower method of working, such as by press forging or rolling, isused, then the zinc content may be somewhat greater, e. g. from 0.5 to 4per cent, while the cadmium content may be 1 to 10 per cent. Extrusionmay be employed .on our alloys with zinc content of 0.5 'to 8 per centwhile containing from 1.0 to 12 per cent of cadmium, the amount ofcadmium being preferably in excess of the zinc. Alloys suitable forcasting may have cadmium and zinc present each in amount exceeding 0.5per cent and under 12 per cent, the total. of the two alloying metalsbeing less than 20 per cent of the alloy.

In comparison with the present commercially available magnesium basealloys, we have found our new alloys to be very resistant to corrosion.Tests made in 3 per cent salt solutions by the well known alternateimmersion method indicate these new alloys are well adapted to uses inwhich superior resistance to corrosion is required. The known methodsfor heat treating magnesium base alloys may be applied to our new alloysadvantageous improvement in mechanical properties such as tensilestrength, yield point, and hardness, particularly where the zinc contentis over approximately 2 per cent.

@ther modes of applying the principle of our invention may beern loyedinstead of the one explained, change eing made as regards theproportions of the in edients employed within the limits speci ed,provided the ingredients stated by any of the following claims or theequivalent of such stated ingredients be employed.

We therefore particularly point out and distinctly claim as ourinvention 1. As a product, a magnesium base alloy composed of the metalsmagnesium, cadmium, and zinc, wherein the magnesium content is in excessof 80 per cent and cadmium and zinc are present each in amounts of over0.5 per cent and the amount of cadmium and zinc together is less than 20per cent of the total.

2. As a new product,-a magnesium base alloy composed of in excess of 80per cent magnesium and from 0.5 to 8 per cent of zinc an from 1 to 12per cent 0 cadmium, the amount of the cadmium being in excess of the mm.

3. As a new product, a magnesium base alloy composed of from 0.5 to4fper cent of zinc and from 1 to 10 per cent 0 cadmium, the balancebeing magnesium.

4. As a new product, a magnesium base alloy composed of from 1 to 4 percent of zinc, about 6 per cent of cadmium and the balance magnesiumj 5.As a new product, a magnesium base alloy composed of from 0.5 to 2.0 percent of zinc, from 1 to 10 per cent of cadmium and the balancemagnesium.

6. As a new product, a magnesium base alloy composed of in excess of percent of magnesium and from 0.5 to 12 per cent of each of the metalscadmium and zinc,the total amount of the cadmium, and zinc being lessthan 20 or cent of the alloy.

Signe 'by us this 9th day of February,

JOHN A. GANN. FRED L. REYNOLDS.

